This invention relates to antibacterial compounds for Ralstonia solanacearum. Bacterial wilt which affects tomatoes, egg plants, green peppers, tobacco plants, Japanese radishes, strawberries and the like is a kind of bacterial disease caused by Ralstonia solanacearum. Ralstonia solanacearum is known for its very high spreading velocity, and its secondary invasion is very strong. Thus, the bacterial wilt caused thereby can be a source of a severe damage particularly for green-house cultivation and repeated cultivation. This invention relates to antibacterial compounds capable of dependably suppressing such bacterial wilt even if used at a low concentration.
Conventional methods of suppressing bacterial wilt included disinfection by the solar heat, root growth restriction by means of sheets and grafting on resistant cultivar as rootstocks. With these conventional methods, however, manifestation of effects is extremely insufficient. Use of a disinfectant has also been attempted but the use of a disinfectant has bad effects not only on the plants and the soil but also on the workers, besides suppressing bacterial wilt. In view of the above, Japanese Patent Publication Tokkai 7-228502 disclosed the use of synthesized 3-(3-indolyl) butanoic acid and its salts as antibacterial compounds capable of suppressing Ralstonia solanacearum. These compounds have the desirable characteristic of being capable of selectively inhibiting the growth of Ralstonia solanacearum which is the cause of bacterial wilt and hence suppressing bacterial wilt without having any ill effects on other bodies. Prior art synthesized 3-(3-indolyl) butanoic acid and its salts have the disadvantage, however, in that they must be used at a relatively high concentration in order to selectively inhibit the growth of Ralstonia solanacearum.